Anatomy and Physiology Sixth Edition Rod R Seeley

+ Anatomy and Physiology, Sixth Edition Rod R. Seeley Idaho State University Trent D. Stephens Idaho State University Philip Tate Phoenix College Chapter 7 Lecture Outline* *See Power. Point Image Slides for all figures and tables pre-inserted into Power. Point without notes. Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. 9 -1

+ n 9 -2 Chapter Plan The Muscular System Study Guide n Projects n One section a day – Due Fridays Research: Diseases of the Muscular System n Location of Superficial Muscles (Group QUIZ) n Quick Recall (GROUP QUIZ) n Mastery Learning Activity (INDIVIDUAL QUIZ) n Muscle Fatigue Lab n Chicken Wing Dissection Final Learning Challenges (GROUP QUIZ) n The Muscle System Tour n Muscular System Lab (part 2 & 3 only) n n Lab: Quizzes/Exams n Quizlet n Parts of a Muscle Quiz n Chapter Test n Case Studies n n The Tired Swimmer Media: n Video of runner/sprinter

+ 9 -3 Key Vocabulary

+ Chapter 7 Muscular System: Histology and Physiology 9 -4

+ Muscular System Functions n Body movement n Maintenance of posture n Respiration n Production of body heat n Communication n Constriction of organs and vessels n Heart beat 9 -5

+ Properties of Muscle n Contractility n Ability of a muscle to shorten with force n Excitability n Capacity of muscle to respond to a stimulus n Extensibility n Muscle can be stretched to its normal resting length and beyond to a limited degree n Elasticity n Ability of muscle to recoil to original resting length after stretched 9 -6

+ Muscle Tissue Types n Skeletal n Attached to bones n Nuclei multiple and peripherally located n Striated, Voluntary and involuntary (reflexes) n Smooth n Walls of hollow organs, blood vessels, eye, glands, skin n Single nucleus centrally located n Not striated, involuntary, gap junctions in visceral smooth n Cardiac n Heart n Single nucleus centrally located n Striations, involuntary, intercalated disks 9 -7

Connective Tissue, Nerve, Blood Vessels 9 -8 n Connective tissue n Endomysium n Perimysium n Epimysium n Nerve or Fascia and blood vessels n Abundant

9 -9 Checking in… n n Put the following in order from greatest to least n Endomysium n Perimysium n Epimysium What do each of these connective tissue surround?

+ Parts of a Muscle 9 -10

+ 9 -11 Quick Recap n n Put these muscle parts in order from largest to smallest n Myofibril n Skeletal muscle n Muscle fiber n Muscle fasciculi n Myofilament (actin or myosin) On which of these muscle parts would you find: n Sarcolemma? n Sarcomere? n Capillary and nuclei? n Mitochondria?

+ Structure of Actin and Myosin 9 -12

Components of Sarcomeres + 9 -13

+ Sliding Filament Model (p. 163) n n Actin myofilaments sliding over myosin to shorten sarcomeres n Actin and myosin do not change length n Shortening sarcomeres responsible for skeletal muscle contraction During relaxation, sarcomeres lengthen 9 -14

+ Sarcomere Shortening 9 -15

Physiology of Skeletal Muscle n Nervous n 9 -16 system Controls muscle contractions through action potentials n Resting membrane potentials n Membrane voltage difference across membranes (polarized) n n n Inside cell more negative and more K+ Outside cell more positive and more Na+ Must exist for action potential to occur

Ion Channels 9 -17 n Types n Ligand-gated n Example: neurotransmitters n Voltage-gated n Open and close in response to small voltage changes across plasma membrane

Action Potentials 9 -18 n Phases n Depolarization n n Repolarization n n Like camera flash system Propagate n n Return of resting membrane potential All-or-none principle n n Inside plasma membrane becomes less negative Spread from one location to another Frequency n Number of action potential produced per unit of time

+ Gated Ion Channels and the Action Potential 9 -19

+ Action Potential Propagation 9 -20

Neuromuscular Junction n Synapse or NMJ n n Presynaptic terminal Synaptic cleft Postsynaptic membrane or motor end-plate Synaptic vesicles n n Acetylcholine: Neurotransmitter Acetylcholinesterase: A degrading enzyme in synaptic cleft 9 -21

+ Function of Neuromuscular Junction 9 -22

Excitation-Contraction Coupling 9 -23 Muscle fiber n Mechanism where an action potential causes muscle fiber contraction n Involves n n n Sarcolemma Transverse or T tubules Terminal cisternae Sarcoplasmic reticulum n Releases Ca 2+ Troponin n Ca binds to this

+ Action Potentials and Muscle Contraction 9 -24

+ 9 -25

+ Cross-Bridge Movement 9 -26

+ 9 -27 Checking in… n Rigor mortis (stiffness + death) is a condition in which the muscles of a deceased person remains rigid. Explain why this might happen using what you learned about cross-bridges and muscle contraction. n Answer: A new ATP must bind to mysoin before the crossbridge can be released. When ATP is not available after a person dies, the cross-bridges that have formed are not released, causing the muscle to become rigid

+ 9 -28 Predict… n n Predict the consequences of having the following conditions develop in a muscle in response to a stimulus: n Inadequate ATP is present in the muscle fiber before a stimulus is applied n Adequate ATP is present within the muscle fiber, but action potentials occur at a frequency so great that calcium ions are not transported back into the sarcoplasmic reticulum between individual action potentials Answer: n Energy from ATP is stored on the myosin heads. W/O ATP, no cross -bridges are formed, no muscle contraction n Ca 2+ is needed to bind to troponin molecules which exposes myosin attachment sites for cross-bridges to form. No Ca 2+, no muscle contraction

+ 9 -29 More to check in… n Why does a person’s body temperature increase after exercise? Why does a person shiver?

9 -30 Muscle Twitch n Muscle contraction in response to a stimulus that causes action potential in one or more muscle fibers n Phases n Lag or latent n Contraction n Relaxation

Stimulus Strength and Muscle Contraction n All-or-none fibers n n n Sub-threshold stimulus Threshold stimulus Stronger than threshold n Motor units Single motor neuron and all muscle fibers innervated n Graded n law for muscle Contraction of equal force in response to each action potential n n 9 -31 for whole muscles Strength of contractions range from weak to strong depending on stimulus strength

Multiple Motor Unit Summation n. A whole muscle contracts with a small or large force depending on number of motor units stimulated to contract 9 -32

Multiple-Wave Summation 9 -33 n As frequency of action potentials increase, frequency of contraction increases n Incomplete tetanus n n Complete tetanus n n Muscle fibers partially relax between contraction No relaxation between contractions Multiple-wave summation n Muscle tension increases as contraction frequencies increase

Types of Muscle Contractions + n Isometric: No change in length but tension increases n Postural n Isotonic: muscles of body Change in length but tension constant n Concentric: Overcomes opposing resistance and muscle shortens n Eccentric: Tension maintained but muscle lengthens n Muscle tone: Constant tension by muscles for long periods of time n Keeps back & legs straight, head held upright, abdomen from bulging 9 -34

+ Fatigue 9 -36 n. Decreased capacity to work and reduced efficiency of performance n. Types n Psychological n Depends on emotional state of individual n Muscular n Results from ATP depletion n Synaptic n Occurs in NMJ due to lack of acetylcholine

Energy Sources + n ATP provides immediate energy for muscle contractions from 3 sources n Creatine n phosphate During resting conditions stores energy to synthesize ATP n Anaerobic n Occurs in absence of oxygen and results in breakdown of glucose to yield ATP and lactic acid n Aerobic n n respiration Requires oxygen and breaks down glucose to produce ATP, carbon dioxide and water More efficient than anaerobic ü Where does anaerobic respiration occur in the cell? Aerobic? 9 -37

+ 9 -38 Checking in… n Scenario: After a 10 -mile run with a sprint at the end, a runner continues to breathe heavily for a time. Indicate the type of metabolism that is producing energy during the run, during the sprint, and after the run n Answer: n During the run, aerobic respiration is used to break down glucose to produce ATP, CO 2 and H 2 O. n During the sprint, anaerobic respiration is used to yield small amounts of ATP and lactic acid n After the run, respiration rate and volume remain elevated to pay back the O 2 debt. This is needed to convert lactic acid to glucose, replenish ATP and creatine phosphate in muscle fibers and replenish O 2 in the lungs, blood, and muscles

Slow and Fast Fibers + n Slow-twitch or high-oxidative n Contract more slowly, smaller in diameter, better blood supply, more mitochondria, more fatigue-resistant than fast-twitch n Fast-twitch or low-oxidative n Respond rapidly to nervous stimulation, contain myosin to break down ATP more rapidly, less blood supply, fewer and smaller mitochondria than slow-twitch n Distribution n Most of fast-twitch and slow twitch muscles have both but varies for each muscle n Effects of exercise n Hypertrophies: Increases in muscle size n Atrophies: Decreases in muscle size 9 -39

+ Checking in… n When eating turkey, which do you prefer white or dark meat? n Why is there such a difference? n Answer: n White meat (especially in chicken breast) is composed of mostly fast twitch muscle fibers – good for contracting rapidly for short periods of time and fatigues quickly n Dark meat (especially in the chicken legs or duck’s breast) is composed myoglobin, richer blood supply and stores oxygen 9 -40

Smooth Muscle 9 -41 n Characteristics n n Not striated Dense bodies instead of Z disks as in skeletal muscle n n Have noncontractile intermediate filaments Ca 2+ required to initiate contractions n Types n Visceral or unitary n n Function as a unit Multiunit n Cells or groups of cells act as independent units

Cardiac Muscle + n Found only in heart n Striated n Each n Has cell usually has one nucleus intercalated disks and gap junctions n Autorhythmic n Action period n Ca 2+ cells potentials of longer duration and longer refractory regulates contraction 9 -46

Effects of Aging on Skeletal Muscle + n Reduced muscle mass n Increased time for muscle to contract in response to nervous stimuli n Reduced stamina n Increased recovery time n Loss of muscle fibers n Decreased density of capillaries in muscle 9 -47

+ 9 -48 Disorders of Muscle Tissue n Cramps n Fibromyalgia n Hypertrophy & Atrophy n Muscular Dystrophy n Myasthenia Gravis n Tendinitis